"Mir, Ubuntu's in-progress replacement for the X Window System, is being used internally at Ubuntu developer Canonical and will be available to all users in the next version of the operating system. Mir was announced in March, with Canonical saying that a new display server is needed to power the Unity interface across desktops, phones, and tablets." Anyone here experience with Mir? Is it any good? any downsides?

I think the point is that nobody except Ubuntu wants it. Maybe that is the point, but I remember them in 2004 having a big campaign about being friendly, community etc and tbh I think we know it is all bullshit.